Today while accelerating on the highway, the transmission seemed to pull off a few times under load. Almost like it was skipping/ slipping. I then tried to downshift hard on a merge, and the power was there somewhat but seemed to be skipping but managed to redline without totally slipping out of gear..

After that hard accel, I noticed a constant loud vibration... Almost as though the driveshaft was hitting the underbody .. Got louder the faster I went, and when accelerating. (Can’t really hear it when not on the throttle)

anyways. I got home and used my scan tool to see what’s up. Misfire cylinder 3, and a couple codes for Secondary air injection both banks.. No codes in trans that I could see. But then again I don’t have a bmw tool. (I got my ista laptop on eBay In the mail TODAY, and it doesn’t work) Yea I’m having a bad day lol

I’m assuming I should start with looking under the car for signs of a defective guibo, or driveshaft ?

Then I’ll try swapping coils to see if misfire follows. As for the misfire, it isn’t bad at idle until you engage the gear into drive or reverse. The car almost died when getting off the highway when in gear.